Australia's competition regulator has given the airlines Qantas and Emirates final approval to form a five-year global alliance, while requiring that they continue to compete with each other on flights between Australian and New Zealand.

The Australian Competition and Consumer Commission also said there would only be slight benefits to the public from the partnership. "The ACCC is satisfied that the alliance is likely to result in material, but not substantial, public benefits," the ACCC chairman Rod Sims said in a statement.

The ACCC had already granted interim approval, allowing the Australian and Dubai-based carriers to share flights between Australia and Europe, North Africa, the Middle East and Asia.

Wednesday's final ruling, which lasts for five years, requires each airline to maintain its existing capacity on four overlapping routes to New Zealand: Sydney-Auckland, Melbourne-Auckland, Brisbane-Auckland and Sydney-Christchurch.

"On these routes the ACCC is concerned that Qantas and Emirates will have the ability and incentive to reduce or limit growth in capacity in order to raise airfares," Sims said.

The requirement to maintain capacity on these four routes, which account for about 65% of all seats between Australia and New Zealand, would be subject to a review to consider whether increases in the minimum capacity were warranted. "With this condition the ACCC is satisfied that the relevant net public benefit tests are met," the ACCC said.

Qantas and Emirates also plan to co-operate on sales, marketing and pricing. The alliance was a key plank in Qantas chief executive Alan Joyce's bid to return the company's international operations to profitability.

Under the partnership Qantas will use Dubai rather than Singapore as the stopover point for its flights to London. The first Qantas flight to London via Dubai departs on Sunday.

Qantas signed a 10-year partnership with Emirates in September last year, ending a 17-year relationship with British Airways.

Neither Emirates nor Qantas takes a stake in the other under the deal.

Joyce and the emirates president, Tim Clark, said they welcomed the ACCC decision.